1. Field of the Invention
The present invention relates to a resin composition with good stretchability comprising a saponified ethylene-vinyl ester copolymer and its use. The resin composition of the present invention and a shaped article having a layer comprising such the resin composition have gas barrier properties due to the saponified ethylene-vinyl ester copolymer.
2. Description of the Prior Art
Polyvinylidene chloride (PVDC) is one of resins having good gas barrier properties, and packaging films or sheets having a layer comprising PVDC are widely used. However, the films having the PVDC layer may be avoided because of the inclusion of chlorine atoms.
Saponified ethylene-vinyl ester (EVOH) copolymers are known as the resin materials having good gas barrier properties and transparency. However, it is difficult to produce a film of EVOH, since EVOH has insufficient stretchability.
A known film comprising EVOH is a film obtained by stretching a raw sheet (unstretched sheet) comprising an EVOH layer and a polyamide (PA) layer having resistance to pin-hole formation (flexibility) which is laminated on the EVOH layer (see JP-A-52-115880). Still, the sufficiently stretched film has not been obtained since EVOH has the insufficient stretchability.
JP-A-53-88067 and JP-A-59-20345 disclose resin compositions comprising EVOH and various plasticizers, but those compositions have drawbacks such as significant decrease of the gas barrier properties, bleeding of the plasticizers, and the like.
Compositions comprising EVOH and PA, which are disclosed in JP-A-52-141785, JP-A-58-154755, JP-A-58-36412, JP-B-44-24277, JP-B-60-24813 and JP-A-58-129035, have a drawback that a large amount of gel forms in the composition.
A composition comprising EVOH and other thermoplastic resin (e.g. ethylene-acrylate copolymers) disclosed in JP-A-61-220839 has insufficient transparency.
JP-A-61-233537 discloses a multilayer container produced by blowing a laminate comprising an EVOH layer and a pair of layers made of ethylene-a-olefin copolymer which are laminated on respective surfaces of the EVOH layer. However, this container has streaks caused by stretching irregularity of EVOH and therefore unsatisfactory appearance.